After a lot of research, headaches and trial and error, it appears that the new Windows 10 update 1903 is forcing a BIOS update to version 306 on ASUS GL502VS and other models. This is causing an issue when the Samsung 860 EVO and other SATA SSDs are installed as D drives (not boot drives). On startup the computer will get stuck at the ROG logo screen. If you remove the Samsung SATA SSD the computer will start up fully. If you try to flashback to BIOS 302 the Samsung Drive will not cause problems. However, the new windows version will try to auto udpate the BIOS again any time you restart. This forces you to roll back windows to the previous version and flashback to BIOS 302. Until either Samsung and/or ASUS figures out whats going on, updating Windows is not possible for me and other users of certain ASUS models.
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